Food cache

A few years ago a sheet of roof insulation arrived in the edge of the wood at the nature reserve - probably blown off a passing truck. I should have removed it...but didn't, and now various rodents make use of its shelter for nests and food caches. I looked under it today and found this hoard of cherry stones from which the kernels have been eaten. The ones with small holes in otherwise intact nuts have almost certainly been eaten by wood mice - the extra photo shows another cache, less than half a metre away, which looks to be entirely down to wood mice. However, this collection includes lots of stones that have been cracked in half and this is normally a good sign of hawfinch activity. Not only are hawfinches not recorded for the reserve (but are seen nearby), but how would the stone halves get under the insulation sheet? It's a bit of a puzzle. The hoarder has to be a small rodent, but none are known to deal with stones this way. It looks like another investigation needs to be started!!